[InlineCost] Refactor the checks for different analyses to be a bit more

localized to the code that uses those analyses.

Technically, this can change behavior as we no longer require the
existence of the ProfileSummaryInfo analysis to use local profile
information via BFI. We didn't actually require the PSI to have an
interesting profile though, so this only really impacts the behavior in
non-default pass pipelines.

IMO, this makes it substantially less surprising how everything works --
before an analysis that wasn't actually used had to exist to trigger
*any* profile aware inlining. I think the new organization makes it more
obvious where various checks for profile signals happen.

Differential Revision: https://reviews.llvm.org/D36710

llvm-svn: 310888